1. Technical Field
The present invention relates to a field emission device, a display adopting the same, and a method of manufacturing the same and, more particularly, to a field emission device which has improved focusing effect of electron beams, a display adopting the same, and a method of manufacturing the same.
2. Related Art
Display devices, which are the principal conventional information transmission media, have been typically used as monitors of PCs and TV receivers. Such display devices are largely classified into cathode ray tubes (CRTs) which use high-speed emission of hot electrons, and flat panel display devices which have been rapidly advancing. The flat panel display devices include a liquid crystal display (LCD), a plasma display panel (PDP), and a field emission display (FED).
In the field emission display, a strong electric field is formed between a field emitter and gate electrodes disposed on a cathode at a constant interval, so that electrons are emitted from the field emitter so as to impact on phosphors of an anode, thereby emitting light. The field emission display is a very thin display device, and is therefore attracting great attention in view of its thinness of several centimeters in overall thickness, wide viewing angle, low power consumption and low fabrication cost.
The field emission display utilizes substantially the same physical principle as the CRT. In other words, emissions from the cathode are accelerated so as to collide with the anode so that phosphors coated on the anode are excited so as to emit light of a particular color. Unlike the CRT, however, the field emission display uses a cold cathode material as an electron source. The field emission display includes a cathode formed on a substrate. In addition, a gate electrode is formed as an electron extracting electrode on an insulating layer. A field emitter is provided within a hole through which part of the cathode is exposed.
In the field emission display having the above-described structure, however, if the trajectories of electron beams are not controlled, a desired color cannot be exactly displayed at a given pixel. Therefore, there is a demand for an electron beam trajectory control technique which enables electrons emitted from the field emitter to be accurately transmitted to a desired pixel on an anode coated with a phosphor material.
A second insulating layer is additionally deposited over a gate electrode, and a focus gate electrode for controlling electron beam trajectories is formed thereon.
Overfocused electrons deviate from a target phosphor layer region and excite a phosphor layer in another region, which results in deterioration of color purity. This undesirable result is caused by inconstant protruding directions of a carbon nanotube (CNT) used as an electron source.
To avoid the above-described concerns, U.S. Pat. No. 5,920,151 discloses a field emission display (FED) having an imbedded focusing structure. However, it requires an outgassing process for exhausting volatile gas from an organic material formed on a focus gate electrode, i.e., polyimide, making the disclosed FED difficult to apply to a large-screen display field.